In most buildings and houses a large amount of water, used during showering or the sink, goes directly down the drain. Rainwater also flows directly from the roof into the drains. This “grey” water is slightly soiled and, after cleaning, may be used for flushing of toilets, cleaning activities or watering the garden.
A grey water system consists of a storage tank with a filter. The storage tank collects rainwater and lightly soiled water from the building. The water is filtered prior to being stored. From storage, the grey water can be pumped up for use in toilets, outside taps, watering the garden or washing the car. If the storage empties during a dry period, flushing is switched to the mains water feed.